The ISIS militants running people out of towns like the one we just heard about are part of an extremist Sunni Muslim movement. They draw on sympathy from at least some Sunnis in the areas they've conquered in both Syria and Iraq, as well as backing from others around the region.

NPR's Deborah Amos has reported extensively on ISIS and wrote a book a few years ago about the upheaval of cities in the Middle East. And she joins us now from New York. Hi, Deb.

DEBORAH AMOS, BYLINE: Hello.

SIEGEL: First, most analysts agree that to defeat ISIS or the Islamic State, as it calls itself, you need to get the Sunnis of Iraq and Syria to turn away from them, which are implies that Sunnis in both countries now support them. Why?

AMOS: Well, you have to look at this historically. Sunni Muslims are the majority in the Arab Middle East. They've ruled this region for generations, and they'll tell you that they believe that's the natural order of things.

Now, in recent history you've had the rise of political Shiite Muslim movements. The revolution in Iran, Hezbollah and Lebanon. That's the regional picture in 2003 when in Iraq the U.S. invasion turned the existing Sunni order on its head. For the first time, Iraqi Sunnis - now, they were told wrongly that they were the majority. They had to share power with the Shiites, and that didn't go well. Sectarian politics shut Sunnis out of the security services, top government jobs. Their political leaders were jailed. Iraqi Sunnis were seen by Shiites and, particularly, the state security apparatus as terrorists unless proved otherwise.

So their support for ISIS now is a sign that Sunnis not only feel oppressed, they also believe they have no other option. You saw the same thing in Syria where ISIS matured on the battlefield when the revolution turned violent. They crossed the border. They came and helped them out as Sunnis saw themselves getting slaughtered by the Assad regime.

SIEGEL: How does ISIS recruit, and who tends to join?

AMOS: Here's what Iraqi Shiite authorities say. It's mostly young men between the ages of 16 and 25, primarily poor, unemployed with little education. But we have also seen that ISIS attracts the educated. I met a young man last year on the Turkish border - 21 years old, university student in engineering. He'd fought with some of the other rebel groups, but he told me that ISIS was the real deal. He was willing to give up smoking, drinking, going to nightclubs. He was growing his beard.

There are rules when you join ISIS - responsibilities when you join. That's something that's not on offer from these governments. ISIS runs clinics. They collect taxes. They provide services. This is a strategic leap from what al-Qaida did.

SIEGEL: Well, let's talk about some big Sunni powers in the region - Saudi Arabia, the Gulf states, Turkey. Can those countries represent Sunni interests sufficiently well to step up the campaign against ISIS?

DEBORAH AMOS, BYLINE: Robert, to some degree, but in the Gulf and even in Turkey, these radical Islamists were a useful tool for their policies. Turkey wanted the government in Syria to fall, so we saw that they turned a blind eye to radicals crossing into Syria. And in the Gulf, of ISIS is a useful tool in the regional competition against Iran, the major Shiite power. Now, we know that the Obama administration is working to build this regional coalition, but they're going to have to get all these powers on the same page against ISIS.

SIEGEL: Let's go back to what happened in Iraq. In 2006 there was a popular revolt against al-Qaida in Iraq. Sunnis joined together in something called the Sunni awakening. They got help from U.S. troops who surged at that moment, and they got rid of those militants. Is there likely to be another awakening - a Sunni reawakening?

AMOS: I think that's what political leaders across the region are hoping. There's some signs that Sunnis in Iraq are turning against the brutal ways of ISIS. You see Arab tribes organizing. Some hit-and-run operations have been reported in the Iraqi city of Mosul. In Syria, the rebels there turned against ISIS more than a year ago.

But here's the thing. Everybody in the region learned from the awakening, including ISIS. So here's an example. Recently in Deir ez-Zur in eastern Syria, a Sunni Arab tribe there did turn against ISIS, but 700 of there people were killed, and ISIS declared the entire tribe apostates. That's about 70,000 people who they say can be killed anywhere. The tribal chief put out a call for help, but he didn't get an answer.

So as long as some Sunnis in Iraq and Syria see ISIS as a better bet than the sectarian governments in Baghdad and Damascus, I don't think you're going to see an awakening.